We have used a series of Chinese hamster ovary (CHO) subclones to investigate the molecular mechanisms underlying the surface phenotypes described by concanavalin A (Con A)-induced receptor mobility and Con A-initiated cell agglutination. Our work has clearly demonstrated that there is no necessary correlation between Con A-initiated cell agglutination and such properties as enhanced lectin receptor mobility, microvilli distribution or the absence of the LETS protein from the cell surface. Furthermore our work has so far failed to point out any change in membrane composition which can be unequivocally associated with control of lectin receptor mobility, although we do have some preliminary evidence implicating phosphorylation of membrane peptides in the control of receptor mobility. Using Con A affinity chromatography we have successfully isolated microgram quantities of five Con A binding glycoproteins. We have prepared antibodies to these Con A-binding glycopeptides and intend to use these antibodies to follow the mobility of discrete Con A binding glycoproteins. We hope to use this work to complement the work already completed relating to the mobility of the generalized class of Con A receptors. Recently we have demonstrated that the addition of low concentrations of Con A to both whole cells and isolated membranes produces a Scatchard plot clearly indicative of a positively cooperative phenomenon within the Con A binding process. Furthermore we have found that binding of low concentrations of Con A to whole cells increases the availability of sialic acid groups to labeling with NaIO4/NaB3H4. We are presently investigating the molecular mechanisms underlying these phenomena. Our preliminary evidence suggests a role for the actin cables in both the positive cooperativity phenomenon and the "redistribution" of cell surface sialic acid residues.